[R] How to set default encoding for sourced files

[Andrew Hart]

Hi there. I'm working with some utf-8 incoded csv files which gives me 
data frames with utf-8 encoded headers. This means when I write things like
dat$proporción
in an R script and then source it, I have to make sure the R script is 
incoded using utf-8 (and not latin1) and then I also have to explicitly 
tell R that the encoding is utf-8 every time I source the file, that is, 
I need to type
source("sr.R", encoding="utf-8").

Sure, I could eliminate accents and so forth from the headers by 
renaming the data frame columns, and I have done and do do this, but I 
shouldn't be required to do this just to avoid encoding issues.
We're living in the 21st century and imho Unicode-based encodings should 
be the de facto standard these days. I'm aware that R is pretty clever 
and stores the encoding along with the string value in all character 
objects and then converts on the fly as necessary. However, Almost 
everything I work with is in utf-8 or ASCII (which is compatible with 
utf-8 anyway),
so I'd like R to behave as though it does everything natively in utf-8 
so I don't have to worry about it.
Is there something in Rprofile.site or the user Rprofile or an 
environment variable I can set or some other way to instruct R to always 
assume that input stream encodings will be utf-8  unless otherwise 
specified? This way, I would only ever have to supply an encoding or 
fileEncoding argument to specify "latin1" if I happ	en to encounter it.

Many thanks,
Andrew.